Inert gases such as helium, argon, and nitrogen are routinely used in laboratory and industrial applications to prevent the oxidation of chemical species or of the materials used in the construction of equipment. Because these gases are produced via separation techniques, they can be expensive, and methods for their usage reduction and/or recycling are commonly employed. For most recycling methods, purification of the gas prior to reuse is required.
When purification requires the removal of oxygen-containing species (O2, CO2, CO, H2O, etc.), a well-known method for purification is to expose the “used” or impure gas to a metal-based catalyst such as nickel, which reacts to trap the oxide species via chemisorption and/or oxidation. Typically, when the reaction sites on the catalyst are consumed, the catalyst is regenerated for reuse.
In the case of nickel gas purifiers, chemisorption reactions are reversed by exposing the nickel to hydrogen gas, such that the metal is returned to its base or elemental form via the following reactions:Ni(CO)x+3xH2→Ni+xCH4+xH2ONiO+H2→Ni+H2ONi(CO)x+xH2→Ni+x/2CH4+x/2CO2 
Purge gases are commonly used in fiber draw furnaces constructed with graphite materials for the formation of optical fibers in order to prevent damage to the furnace by room air intrusion. Upon exiting a draw furnace, the typical furnace purge (helium and argon) contains trace amounts of carbon monoxide (200-600 ppm) and 1-10 ppm HCl and/or chlorine gas. When this purge is collected for recycling, typically, some amount of nitrogen, carbon dioxide, oxygen, and water are collected with the target purge gas, the concentration of these gases being dependent on the design of the collection system and the collection rate/flow. Impurities in the purge gases used in such furnaces can result in accelerated oxidation of the materials used for the construction of the draw furnace. Over time, this oxidation leads to end products of lesser quality and/or the need for costly replacement parts and repairs. Further, chlorine compounds need to be removed from the draw furnace to prevent buildup or concentration in the recycled gas stream and associated corrosion damage.
Commercial nickel catalyst gas regeneration systems, when used as directed, can leave behind undesirable byproducts which in turn can release gaseous impurities into the processed gases at concentrations of over 500 parts per million. What is needed is a more thorough and effective method of regenerating the nickel catalyst such that fewer impurities are present in the end product.